Discharge tube electrode



Dec. 20, 1932. F. HOTCHNER DISCHARGE TUBE ELECTRODE Filed March so. 1929.mVE/vToR Patented 2c, 1932.

UNITED STATES FRED HOTGHNEB, LOB ANGIHJES, CALIFORNIA DISCHARGE TUBEEIMUI'RODE Application filed larch 80, 1929. Serial No. 851,196.

This invention relates to a discharge tube electrode, and has for itsobject the roduction of an electrode such as might e used for ionizationconductor lights. The elec- 5 trode of the present invention possessescertain desirable characteristics in the abovementioned use, being freefrom certain undesirable characteristics at present a problem in theart; these ends being accomplished by new and novel types ofconstruction.

As at present understood by the applicant this device is new to theentire art of vacuous or vapor electric devices and its usefulness isnot limited to ionization conductor devices, but also extends to devicesessentiall v vacuous such as X-ray tubes. Therefore the disclosure hasbeen contrived to enable one skilled in the art to understand thetechnique of the glass manipulation in the manufacture of the typicalelectrodes shown in order that the device can be reproduced and appliedto devices of the cla$ mentioned. Further, to enable those skilled inthe art to utilize this device as an electrode in gaseous dischargetubes, a theory is advanced of the operation of the same when so used.It is not intended to limit the invention to ionization conductordevices, thereby, nor is it intended to limit the invention by thetheory of operation advanced. It is my intention that only suchlimitations be placed upon this invention as are imposed by the priorart and the appended claims.

movement of positive ions towards the emis 5 sion surfaces. Theparticular forms of the prior electrodes are characterized by a cylinderof conducting material, with a bore so reduced in diameter that theopposite surfaces within the cylinder neutralize each other in theireffect on the ions formed. The

In several previously-filled co-pending ap plications I have disclosedelectrodes fordischarge passes to the positive column thru an-orifice soconstricted that such material from the electrode as is vaporized willnot migrate out of the electrode chamber. It is also believed that thesmall orifice also prevents the space charge in the Faraday dark spaceregion from being a factor in what goes on inside of the electrode.

One of the objects of the present invention is to provide an electrodeof the general class described in which a greatly increased area ofemission surface can be realized for a given volume of space. It is alsoan object to provide an electrode in which the opposing emissionsurfaces ma be made very close together without sacri cing in theavailable emission surface. In the case of cylindrical electrodes ifthis distance is reduced to a low value the total surface falls off andcan only be increased by making the electrode very long. When this isdone the current passing to the orifice from the deeper parts of thecylinder interferes with the action of the parts nearer the orifice.Hence a compromise must be made between an insulficiently small bore andthe secondary action described. In the present invention the clearancecan be reduced to an exceedingly small value without experiencing thisdifficulty and hence any desired extent of emission surface can beprovided in a very small elecitrode and high current values can be useThese results are accomplished in a construction which provides for theuse of glass 35 as the shielding medium in such manner as to be readilyunderstood by those familiar with. the construction of vacuum tubes orincandescent lamps. The vitreous elements are designed to finish inlines natural to the medium, thus providing for work that can be madeaccurate and will finish free from strain. The technique is also onethat can be followed by bench fire work, semi-automatic or automaticmachine production.

It is an important feature of the present invention, that in selecting aform of electrode which permits this treatment in the selection ofmaterial, I have also rovided a form of electrode which has an importantphysical idly moving away from the orifice. Thus acrowding eifect isproduced resulting in a balancing component acting against the drift.

I have explained in previous applications the function of a constrictedorifice toprevent the migration of evaporated material. In

. the present invention'I have provided means of five-eighths of an inchthat this invention to make these electrodes with orifices of extremelynarrow openings and for the finishing of the assembly with greataccuracy, notwithstanding the refractory nature of the medium, withwhich we are working.

It is also an object to provide a greatly in- .creased extent of orificein order to reduce the electrical stress in the material and per mit theuse of ordinary lead glass for this purpose if desired.

' Further objects will become apparent from the description whichfollows.

An embodiment of the invention is shown in Figure 1. It is to beunderstood, however, may be made in many other forms than the particularform shown.

In Figure 2 a cross section is shown of the aperture, taken on the line22, in Figure 1, enlarged.

Figure 3 is a perspective view, enlarged, of the inner cone and theinner shield.

Figure 4 is a sectional view of a mold for blowing the inner shield intothe inner cone. The work is shown in the condition of completion of theblowing operation by broken lines.

Figure 5 is a View invention.

Numeral 1, Figure 1, indicates the end of the positive column section ofa gaseous conductor discharge tube, ing tube, and numeral 10 indicatesthe enlarged electrode terminal thereof. This electrode can be made, ifdesired, small enough to be sealed into the end of the main tube withoutan enlargement. Assuming a tube diameter and consuming twenty-fivethousandths of an ampere, this electrode could be made to fit into theend of the tube proper. Assuming a tube as above consuming one tenth ofan ampere, the electrode would appear about as shown in Figure 1. Theelectrode proper of a modified form of the consists of the twoconcentric cones of conducting material 2 and 3, which are both conmamis open to the atmosphere of the tube thru 'the constricted orifice 7.This orifice is such as an illuminatnecte dthe lead-in conductor 7 4,which sealed thru the reentrant stein 5.

Thexcones are separated by a space 6 which properformed by-the shield8,'an d the shield 9 which extend ast the end 11 of the emissionsurfaces. he shield 8 is inreality a bulbof glass which s blown into theinside of the inner cone 2, taking the form thereof and extending pastthe open end to form a wall of the orifice The shield 9 is a cone ofglass fitted while cone 3, extending past the end and forming a wall ofthe orifice. At the small 'endthe shield 9 runs off into the stem 5 thuscom pletely protecting the lead-in conductor 4.

hot to the outside of the outer When the compositions'of the shield andthe stem are difl'erent and have a difi'erentcoefiiw cient of expansion,a section f intermediate glass canbe used between them as indicated by12.

Decided advantages are gained by making the orifice as constricted asthe character of.

the material will permit without the maximum variation bearing asubstantial'proportion to the width of the opening. Thespacing isdetermined in this device by the bosses 13, 14, 15 and 16, formed fromthe material of the inner shield which bear against the outer shield anddetermine both the opening of the orifice and the spacing of theemission surfaces. The cross section in Figure 2 illustrates thefunction of the bosses. It will be appreciated that by blowin the shieldinto a mold such as is shown in igure 4 having depressions indicated by17 and 18 for shaping the bosses that great accuracy can be secured. Asshown by the broken lines in Figure" 4, the bulb is provided with atubulation 19 and a blowing tube 20 which is separated at the tubulationafter the bulb is blown.

The outer shield and the outer cone can also be formed over a mold bymethods which are obvious. The lead in conductor is preferably brazedinto the end of the cone 2 as indicated by 24 and the cone 3 can bepro-, vided with a collar at the small end indicatedby 21 which makes atight fit over the lead in conductor. To provide for adhesion betweenthe cones and the shields, the surfaces of the cones can be berated inthe manner now common in the preparation of the surfaces of copperelectrodes for gaseous conduction tubes.

y 120 In the form of the invention shown in in cross section being rtrodes near the orifice are well protected by the shields and do notpresent any sharp corners to be attacked by the discharge.

Having thusdescribed my invention, what 5 I claim is.

1. In a discharge tube, a pair of electrode elements, having emissionsurfaces disposed parallel to each other and spaced a short distanceapart, and a constricted orifice providing communication between thespace within the chamber defined by the said surfaces and the mainchamber of said dischar e tube.

2. In a discharge tube, a pair 0 electrode elements having emissionsurfaces disposed parallel to each other and spaced a short distanceapart and an extended, constricted orifice providing communicationbetween the space between said emission surfaces and the main chamber ofsaid discharge tube.

3. In an ionization conductor discharge tube for operation onalternating current, an elongated envelope at the opposite ends of whichare disposed electrodes, each of which is provided with a pair ofelements having emission surfaces disposed parallel to each other andspaced a distance apart sufliciently small to reduce the movement ofpositive ions to a low value between said parallel disposed elements.

4. In an ionization conductor discharge tube for operation onalternating current, an

' elongated envelope at the opposite ends of which are disposedelectrodes, each of which is rovided with a pair of elements havinemission surfaces disposed parallel to eac other and spaced a distanceapart sufliciently small to reduce the movement of positive ions to alow value between said parallel disposed elements and shielding meansseparating said elements from the mam chamber of said discharge tube anda constricted orifice providmension parallel with said emission elementsemission elements having surfaces dlsposed parallel to each other andspaced a short distance apart, the space between said surfaces having acup-like form and said s ace being open to the atmosphere ofthe tu eproper thru a constricted orifice extending around the rim of saidspace.

9. In a discharge tube electrode, a cavity electrode element and anotherelement formed to fit within the first said element and to be s acedfrom the same over the greater part 0 the opposing surfaces, the amountof said spacing being determined by.protuberances formed from at leastone of said elements.

10. In a discharge tube electrode, a pair of emission elements ofconducting material having a cup-like form, said elements being formedto nest one within the other with a small spacing between the near facesof said elements, a shield of dielectric material around the" outsideelement and extending past the open end thereof, and a shield within theinner element extending past the open end thereof.

FRED HOTCHNER.

ing comunication thru each shield for the 1 passage of discharges fromthe spaces be-' tween the said emission surfaces to the main chamber ofsaid discharge tube.

5. In a dischar e tube, an electrode having a chamber in ,w ich twoemission surfaces are disposed parallel to each other and spaced a shortdistance apart, and an opening out of said chamber into the main chamberof said discharge tube said opening consisting of a long constrictedorifice the line ofthe longest dimension of said orifice extendingparallel with said surfaces.

55 6. In a discharge tube, an electrode having a chamber within which isdisposed a pair of emission elements havin surfaces disposed parallel toeach other an spaced a short dis- :part, and dielectric shielding means.5 dispos tance to confine the discharge to the surfaces within saidchamber, there being an Q opening therethru providing a communicationbetween the said chamber and the main chamber of said dischar e tube,said opening atively long in a di-

